A letter apparently written by Shmuel Rosenwasser, the Metuallah night watchman kidnaped by Lebanese terrorists, has reached his wife via the International Red Cross. Mrs. Rosenwasser said the letter was written in Czechoslovakian while he normally corresponded in the Rumanian language. She said, however, that it was her husband’s handwriting. The letter inquired about the whereabouts of the family and whether they had enough fuel for heating because the weather in Metullah at this time of year is cold.